Explain the Aggregate Function ' STDEV' in Tableau with Example?

In Tableau, the STDEV function is an aggregate function used to calculate the standard deviation of a numeric field within a specified context or group. The standard deviation measures the dispersion or spread of data points around the mean.

The syntax for the STDEV function in Tableau is as follows:

STDEV(expression)

where the expression is the field or calculation for which you want to calculate the standard deviation.

Here's an example to demonstrate how to use the STDEV function in Tableau:

Suppose you have a dataset that contains information about the test scores of students. You want to calculate the standard deviation of the scores to understand the variability in the performance.

1. Open Tableau and connect to your dataset.
2. Drag the "Score" field to the Columns shelf.
3. In the Marks card, change the aggregation of the "Score" field to "StDev" by clicking on the drop-down arrow next to the field and selecting "StDev." This applies the STDEV function to the "Score" field and calculates the standard deviation of the scores.
4. Tableau will display the standard deviation value in the view.

The result will show you the measure of how the scores deviate from the mean. A higher standard deviation indicates a greater spread or variability in the scores, while a lower standard deviation indicates a more clustered or consistent set of scores.

The STDEV function can also be used with other aggregate functions or in combination with other calculations to perform more complex analyses. For example, you can calculate the coefficient of variation (CV) by dividing the standard deviation by the mean.

In summary, the STDEV function in Tableau allows you to calculate the standard deviation of a dataset, providing insights into the variability and dispersion of data points around the mean.